Field of the Invention
The present description relates to a fluoride fluorescent material and a method for producing the fluoride fluorescent material.
Description of the Related Art
A light emitting diode (LED) is a semiconductor light emitting element produced from a metal compound such as gallium nitride (GaN). Various types of light emitting devices that emit light of, e.g., white color, an incandescent bulb color, or orange color have been developed using such a semiconductor light emitting element in combination with a fluorescent material. Such light emitting devices are enabled to emit, e.g., white light by the light color mixture principle. Well known systems that emit white light include systems using a light emitting element that emits ultraviolet light and three types of fluorescent materials that emit red (R), green (G), and blue (B) light, and systems using a light emitting element that emits a blue light and a fluorescent material that emits, e.g., a yellow light. Light emitting devices that employ systems using a light emitting element that emits a blue light and a fluorescent material that emits, e.g., a yellow light are demanded in a wide variety of fields, including lighting such as fluorescent lamps, car lights, displays, and backlights for liquid crystals. Of these, fluorescent materials used in displays are desired to have both superior light emission efficiency and superior color purity for reproducing colors in a wide range of the chromaticity coordinates. Fluorescent materials used in displays are particularly desired to be advantageously used in combination with color filters and to have an emission peak with a narrow half band width.
Red-light emitting fluorescent materials exhibiting an emission peak with a narrow half band width and having an excitation band in the blue region, fluoride fluorescent materials having, for example, compositions, such as K2AlF5:Mn4+, K3AlF6:Mn4+, K3GaF6:Mn4+, Zn2AlF7:Mn4+, KIn2F7:Mn4+, K2SiF6:Mn4+, K2TiF6:Mn4+, K3ZrF7:Mn4+, Ba0.65Zr0.35F2.70:Mn4+, BaTiF6:Mn4+, K2SnF6:Mn4+, Na2TiF6:Mn4+, Na2ZrF6:Mn4+, KRbTiF6:Mn4+, or K2Si0.5Ge0.5F6:Mn4+ are known (see, e.g., Japanese Patent Application prior-to-examination Publication (kohyo) No. 2009-528429).